swift-testing

# Swift Testing Framework

Modern testing with Swift Testing framework. No XCTest.

## Overview

Swift Testing replaces XCTest with a modern macro-based approach that's more concise, has better async support, and runs tests in parallel by default. The core principle: if you learned XCTest, unlearn it—Swift Testing works differently.

## References

- [Apple Documentation](https://developer.apple.com/documentation/testing)
- [Migration Guide](https://steipete.me/posts/2025/migrating-700-tests-to-swift-testing)

## Core Concepts

### Assertions

| Macro | Use Case |
|-------|----------|
| `#expect(expression)` | Soft check — continues on failure. Use for most assertions. |
| `#require(expression)` | Hard check — stops test on failure. Use for preconditions only. |

### Optional Unwrapping

```swift
let user = try #require(await fetchUser(id: "123"))
#expect(user.id == "123")
```

## Test Structure

```swift
import Testing
@testable import YourModule

@Suite
struct FeatureTests {
    let sut: FeatureType
    
    init() throws {
        sut = FeatureType()
    }
    
    @Test("Description of behavior")
    func testBehavior() {
        #expect(sut.someProperty == expected)
    }
}
```

## Assertion Conversions

| XCTest | Swift Testing |
|--------|---------------|
| `XCTAssert(expr)` | `#expect(expr)` |
| `XCTAssertEqual(a, b)` | `#expect(a == b)` |
| `XCTAssertNil(a)` | `#expect(a == nil)` |
| `XCTAssertNotNil(a)` | `#expect(a != nil)` |
| `try XCTUnwrap(a)` | `try #require(a)` |
| `XCTAssertThrowsError` | `#expect(throws: ErrorType.self) { }` |
| `XCTAssertNoThrow` | `#expect(throws: Never.self) { }` |

## Error Testing

```swift
#expect(throws: (any Error).self) { try riskyOperation() }
#expect(throws: NetworkError.self) { try fetch() }
#expect(throws: NetworkError.timeout) { try fetch() }
#expect(throws: Never.self) { try safeOperation() }
```

## Parameterized Tests

```swift
@Test("Validates inputs", arguments: zip(
    ["a", "b", "c"],
    [1, 2, 3]
))
func tes